#include <stdio.h>

void my_strcat(char *ch1, char *ch2)
{
    int i = 0;
    while (*(ch1 + i))
    {
        i++;
    }
    *(ch1 + i) = ' ';
    int j = 0;
    while (*(ch2 + j))
    {
        *(ch1 + i + 1 + j) = *(ch2 + j);
        j++;
    }
}

int main()
{
    char ch1[100] = "hello";
    char ch2[] = "world";
    my_strcat(ch1, ch2);
    printf("%s\n", ch1);

    return 0;
}